Dynamic X-ray Collimator Control for Dose Optimization
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Solution Overview
Problem
Existing X-ray CT systems fail to optimize X-ray doses for dynamically changing irradiation regions during scanning, particularly in multi-slice CT apparatuses, leading to inefficiencies in image reconstruction and exposure dose management.
Innovation Solution
An X-ray CT apparatus with an X-ray source, collimator, detector, and control units that calculate and adjust the X-ray irradiation region and dose at each view angle, ensuring optimal X-ray distribution and minimizing exposure by dynamically controlling the collimator positions and tube current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the collimator is dynamically controlled to restrict X-ray irradiation to only the region used for image reconstruction, then the exposure dose is reduced, but the X-ray irradiation region dynamically changes during scanning and becomes difficult to calculate and control reliably
Solution Approach 1:
The system calculates the X-ray irradiation region in advance for each view angle based on examination conditions before actual scanning. This preliminary calculation enables the control unit to pre-determine appropriate collimator positions and tube current values, ensuring reliable irradiation control even as the irradiation region dynamically changes during scanning.
Solution Approach 2:
The system dynamically adjusts collimator positions and tube current values according to the calculated irradiation region at each view angle. The collimator is controlled to match the dynamically changing irradiation region, and tube current is adjusted accordingly to maintain optimal X-ray dose distribution throughout the scanning process.
2Area of stationary object
If X-rays are applied with a spreading angle in the body axis direction to cover the irradiation region, then the irradiation coverage is improved, but the X-ray dose distribution becomes difficult to control and optimize
Solution Approach 1:
The system applies different tube current values to different regions within the irradiation area. By calculating appropriate tube current values for each view angle based on the irradiation region, the system optimizes X-ray dose distribution locally across the spreading angle, ensuring adequate coverage while maintaining dose control.
Solution Approach 2:
The system changes tube current parameters dynamically according to the irradiation region and view angle. By adjusting tube current values in response to the spreading angle and irradiation coverage requirements, the system maintains optimal dose distribution across the entire irradiation area despite the geometric spreading of X-rays.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves reliable irradiation of dynamically changing X-ray irradiation regions with optimal X-ray doses, reducing exposure doses and maintaining image quality, especially in the scanning starting and finishing vicinities.
Implementation Method 1
an X-ray source that irradiates an object with X-rays; an X-ray detector that is disposed to oppose the X-ray source and detects X-rays having been transmitted through the object
Implementation Method 2
a collimator that restricts an irradiation range of the X-rays applied from the X-ray source
Data Source
AI summary
In order to provide an X-ray CT apparatus and the like capable of obtaining an optimal X-ray dose for a dynamically changing X-ray irradiation region and reliably irradiating the X-ray irradiation region in a case where X-rays are applied with a spreading angle in a body axis direction, an X-ray CT apparatus 1 dynamically changes an X-ray irradiation region 201 for each view angle during scanning, and a system control device 124 changes a position of an analysis line 300 used to calculate an optimal tube current during scanning according to a position of the X-ray irradiation region 201 at each view angle, so as to obtain an optimal irradiation X-ray dose.